Apparatus for continuous liquid phase separation

ABSTRACT

An apparaus for continuous liquid phase separation, particularly of meta and para cresol, having a desulfonation column in which a plurality of fixed beds are positioned along its length and separated by plenums. Alternative plenums are connected to a source of steam and the plenums not so connected are connected with vapor withdrawal means. A sulfonator is provided to supply feedstock to the column at its top and thin film evaporator provided to concentrate sulfuric acid produced in the column for reuse in the sulfonator. The withdrawal means including condensing means for the separation of water from the volatilized fractions.

United States. Patent ['19] Larkin Jan. 15, 1974 APPARATUS FOR CONTINUOUS LIQUID PHASE SEPARATION [75] Inventor: Barrymore T. Larkin, Middlesex Township, Butler County, Pa.

[73] Assignee: Koppers Company, Inc., Pittsburgh,

22 Filed: Jan. 17,1972

21 Appl. N01:2l8,252

2,552,517 5/1951 Christensen 202/158 2,678,199 5/1954 Koch 202/158 6/1934 Peterkin 202/200 Primary Examiner-Norman Yudkoff Assistant ExaminerS. .l. Emery Att0rrzey-Arland T. Stein et a1.

[5 7] 1 ABSTRACT An apparaus for continuous liquid phase separation,

particularly of meta and para cresol, having a desulfonation column in which a plurality of fixed beds are positioned along its-length and separated by plenums. Alternative plenums are connected to a source of steam and the plenums not so connected are connected with vapor withdrawal means. A sulfonator is provided to supply feedstock to the column at its top and thin film evaporator provided to concentrate sul- [56] References Cited furic acid produced in the column for reuse in the sul- UNITED STATES PATENTS fonator. The withdrawal means including condensing 1,780,977 ll/l930 Leslie 202/158 means for the separation of water from the volatilized 3,082,259 3/1963 Bauer.... 231/2705 fracfions 1,730,891 10/1929 Leslie 202/158 2,493,265 l/1950 Scheibel i. 23/270.5 4 Claims, 1 Drawing Figure It, H2304 m, p Cresol a H 0 l6 l8 2 n l9 J50 P F t 22b 7 m Cresol ic22c 23 24 v L Steam P m, p Cresol Mixture p Cresol Pmmmm 15 m4 3,785; We

m Cresol mm Cresol Mixture p Cresol Film Evupormor Concentrated APPARATUS FOR CONTINUOUS LIQUID PHASE I SEPARATION FIELD OF THE INVENTION BACKGROUND OF THE INVENTION Commercial cresols are coal tar derivatives that occur as isomers ortho, para and meta. The boiling point of o-cresol is approximately 190C, whereas the boiling points of mand p-cresol are about equal. to each other, namely 202.8 and 202.5C., respectively. Thus, substantially pure quantities of o-cresol can be obtained by distillation of the isomeric mixtures. The meta and para fractions are not, however, easily separated because of their essentially identical boiling points. These isomers remain, usually in a ratio of 2:1 metato para-cresol.

Separation of these cresols usually requires chemical as well as physical means, and the processes for carrying out such separations are generally well understood. For example, the meta and para fractions are sulfonated with sulfuric acid to form theirrespective sulfonic acids. The m-cresol sulfonic acid is decomposed by steam at 125C.; the m-cresol distills off and p-cresol' sulfonic acid remains behind undecomposed, United States Pat. No. 656,263. Mixtures of the meta and para cresols can be selectively sulfonated with sulfuric anhydride and separated by distillation in vacuum in the presence of steam, United States Pat. No. I,364,547. The processes utilize the temperature differential between the mand p-cresol sulfonic acid hydrolyzation temperature or the solubility differentials of m-and pcresols to effectuate separation.v

While the chemistry of separation by desulfonation is understood, means for carrying it out in high purity and quantities has not been accomplished. The present invention provides a means for preparing high quantity and purity meta and para cresols.

SUMMARY OF THE INVENTION The present invention is addressed to the continuous separation of meta and para cresols. The continuous separation can be carried out economically and with out the production of unwanted byproducts. Sulfuric acid utilized in the sulfonation of the cresols is reconcentrated for reuse. The aqueous condensates can be dephenolated for reuse as boiler feedstock.

Generally, the apparatus of the present invention includes a sulfonator into which is fed concentrated sulfuric acid and a mixture of meta and para cresol. The sulfonator comprises means for continuously agitating and heating and/or cooling the mixture to. provide complete sulfonation. Residence time of the mixture is approximately 1 hour.

A desulfonation column is provided into which the sulfonated mixture is fed. The sulfonated mixture of cresols is diluted with water at the feed point by means of sprays. The column comprises a plurality of beds each of which is supported by a porous plate- Each of the beds is separated by a plenum. Steam isfed to the column to provide the desired hydrolyzation. temperature for the separation of the diluted sulfonated cresols.

Freferably, the steam is injected into alternating plenu ms and the hydrolyzed cresol product is withdrawn in the vaporized state above each bed from the remaining plenum s. The temperature of the beds vary along the length of the column such that m-cresol is volatilized at the top of the column and 'p-cresol at the bottom. Between the top and bottom of the column mixtures of the rnand p-cresols are withdrawn.

The volatilized cresols are condensed and the water separated therefrom.;The mixture of mand p-cresols from the center of the column are recycled back to the sulfonator, if desired.

As the sulfonated solution proceeds throughthe plurality of beds, sulfur trioxide is formed which combines with the steam to form dilute sulfuric acid. The sulfuric acid is withdrawn at the bottom of the column and fed to an evaporator for concentration and reuse.

Accordingly, the apparatus provides a means for the continuous separation of m-, p-cresols. Other advantages may be seen from a perusal of the following preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a diagrammatic view of a presently preferred embodiment of the apparatus for continuous separation of m-, p-cresols including a sulfonator, desulfonation column and evaporator.

DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT Referring to the drawing, the system includes a sulfonator 10 to which is fed a mixture of m-, p-cre'sols and concentrated sulfuric acid, preferably concentrated sulfuric acid 96 percent, by lines 11 and 12, respectively. Sulfonator ll) includes an agitator 13. While sulfonator l.0 may be constructed from carbon steel or cast iron it is preferable, to fabricate it from stainless because maintenance costs are reduced.

The temperature. of sulfonation is controlled at between l00150C. It may be necessary, however, to utilize cooling-means to maintain the temperature due to high heat generated by the sulfonation reaction. This could be accomplished by providing the sulfonator with a cooling jacket or by circulating the reaction mixture from the sulfonator through a heat exchanger 14 back to thesulfonator. Residence time within sulfonator 10 is about one hour to assure complete sulfonation.

The sulfonated cresols are discharged from sulfonator l0 and fed to theinlet chamber 15a of desulfonation column l5 by line 16. The sulfonated cresols are preferably fed to chamber 15a through spray head 17. The cresols are. diluted with water fed to chamber 15a byline 18 and sprayed, into the cresol spray by spray head 19. While other means for diluting the sulfonated cresol are available, spray provides a very effective dilution. It ispreferable that the ratio of water to sulfonated cresols be approximately 2:1. Thus, the spray heads should be positioned. in such a way as to obtain the mosteffective dilution of the incoming sulfonated cresols.

Column 15 is preferably fabricated from steels having a bonded glass liner. Plastic liners and the like are not well suited for use inthe present invention because of the high temperatures necessary for the separation of p-cresol. Column 15 comprises a plurality of fixed beds 20 supported by permeable plates 21. Between adjacent beds 20 are plenums 22a-n. The number of beds is not critical, but for satisfactory operation it is preferable to have more than three or four.

Beds 20 are preferably of a ceramic packing material such as glazed or unglazed porcelain. The type of packings suitable for use in the present invention include her] saddles, spiral ring, cross-partition rings, raschig rings and the like. The purpose of the packing is to create sufficient residence time within each temperature zone to effectuate hydrolysis and volatilization of the sulfonation stream. The permeable support plates 21 may be made of any suitable material as for example bonded glass steel having openings therein or a permeable ceramic material.

Plenums 22a-n are provided for injecting steam into column 15 from lines 23 connected to a steam generator (not shown). Alternatively, steam could be injected directly into the fixed beds, but such an arrangement would necessitate the use of an elaborate distribution system, and is, therefore, not preferred. Lines 23 include metering valves 24 to control the amount of steam entering each plenum to provide a means for selectivcly establishing temperatures along the length of the column.

Preferably, steam is fed into alternative plenums, for example plenums 22b, 22d. .22n-l. Steam could also be injected into inlet chamber 15a, but this is not deemed necessary. Plenums 22a, 22c. .22n are provided with vapor withdrawal lines or outlet lines 25. By arranging the outlet and inlet lines 25 and 23, respectively, to different plenums, the steam is pulled through the beds contiguous to the inlet. Accordingly, fairly precise temperature zones can be maintained within column 15.

Lines 25 include metering valves 26 to regulate the amount of draw or suction established on each outlet line. Pumps 27 as well as valves 26 are utilized to maintain a negative pressure in the system to lower hydrolysis temperature and increase m-cresol purity and to expedite withdrawal of all of the volatilized fractions.

While a number of pumps 27 have been shown, it is clear that only one pump 27 would be necessary and would be common to all of the condensers 28 that were utilized. Also, pumps 27 could be inserted into line 25 between valves 26 and condensers 28, but this arrangement is not preferred.

The temperature of the uppermost bed is maintained at about l-l20C. In this temperature range the sulfonated mcresol is preferentially hydrolyzed and volatilized and is withdrawn from plenum 22a. The negative pressure as well as the steam pressure draws the steam through the beds, heating them to the desired temperature. The temperature of the solution as it enters the column is adjusted or controlled by the temperatures and volume ratio of the two inlet streams.

Volatilized para-cresol is withdrawn from the bottommost plenum 22n, and the beds immediately above plenum 22n are maintained at a temperature of about l70-l80C. The fractions withdrawn from plenums 22c 22n-2 contain various mixtures of mand pcresols. Since these mixtures have no significant value beyond commerical m-, p-cresol mixtures, they can be used as additional feedstock and are recycled after separation from the water to sulfonator 10. However, if various percentage mixtures are desired, each of these fractions can be separately condensed. Since it is not usually necessary to separate numerous mixture fractions, the number of beds would not be as great and a common pump 27, as shown, could be effectively utilized. V V w j The volatilized fractions are condensed in condensers 28 and the water and cresols separated by liquid phase separation. Preferably three condensers 28 are used; one for each of the substantially pure fractions of mand p-cresol and at least one for the mixtures of cresols. After separation, the mixtures of cresols can be recycled to the sulfonator for resulfonation. If desired, pumps may be used to withdraw the various fractions from the condensers 7 At the bottom of plenum 22n, water and sulfuric acid are collected and fed by line 29 to evaporator 30 for reconcentrating the sulfuric acid and removing water. The concentration of the sulfuric acid collected at plenum 22n depends in large part upon the amount of water fed to column 15 through line 18. Since it is preferable to utilize an excess of water to sulfonated cresol, greater than three times cresol by weight, to hydrolyze the sulfonated cresols, the cresol-stripped acid would be dilute, that is, less than percent concentration. Accordingly, a two stage evaporation would be desirable. The dilute acid could be concentrated to above 75 percent'in a Burke-Mantius evaporator or the like in the first stage and then concentrated to approximately 96 percent in the second stage by a falling film evaporator or submerged combustion unit. If the acid is already greater than 75 percent, only the second The reconstituted acid is recycled to the sulfonator for reuse. The water separated by evaporator 30 and condensers 28 can be recycled to spray head 17 in column 15 or dephenolated and used as boiler feedstock.

Accordingly, it is clear that the apparatus and method employed thereby produce very little if any waste. Economical and ultimately quantitative producl pnp ,.b93h.meta: ndyexeerssszkars aqsqmp bs While the apparatus has been particularly described with reference to m-, p-cresols, the same separation problem exists with respect to 2,4 xylenol and 2,5 xylenol, both of which have a boiling point of 21 1C. The hydrolysis temperatures for their respective monosulfonic acids are 121-125 and ll5ll8C. Thus, it is clear that these xylenols could be separated using the apparatus of the present invention adjusted for temper- The following table is an example of the desulfonation according to the present invention.

TABLE Desulfonation of Sulfonated m, p-Cresols Distillation Conditions Percent Cut Composition,

Wt. Distillation Temp. Pressure Charged Fraction (mm. Hg) I Other C resnls' m-Crcrol p-Cresol l I I8 ca. 760 Steam spargc 10.4 9| 9 2 I I8 l 1.5 10 3 l 18-1 19 l0.6 92 8 4 l l9-l20 10.7 91 9 TABLliF-C'niinued A be s ullonation of Sulfonated p Cresols mammal assumes? i t Percent Cut Composition, of w 1%,: Distillation Temp. P ressure Charged Fraction ("C.) (mm. Hg) Other Cresols m-Cresol p-Cresol 5631's a s3 s4 16 6 1 18 6.6 81 19 7 1 18-1 19 3.9 77 23 8 120 1.8 73 27 9 120-122 End of steam 2.1 66 34 10 122-132 5.1 37 63 11 132-151 12.9 5 87 12 151-170 3.7 8 84 13 96-150 760-9 Vacuum dist. 0.5 12 81 Charged 300.0 g. of 66/34 m. p-Cl'clOl. Recovery 88%. (one pan). Analysis by infrarcd spectrometry. Corrected for any residual solvent.

WITH Fa presently preferred erfi'sdaimehmf mam:

vention has been shown and described, it may otherwise be embodied within the scope of the appended claims.

What is claimed is:

1. An apparatus for continuous liquid phase separation comprising:

a sulfonator for the sulfonation of a feedstock; and

B. ayertical column including i. an inlet located at the top connected to said sulfonator for introducing a stream of sulfonated feedstock into the top of said column,

ii. inlet means for directing a diluent into said sulfo- "'r'ia't'd areas in th'eTop 6f said'columii',

iii. a plurality of vertically spaced apart beds including packing material, adjacent beds defining open chambers there between,

iv. means for introducing steam into alternate open chambers between said packing beds,

v. means for withdrawing volatized fractions from said other open chambers spaces, including at least a pair of condensing means connected to different ones of said withdrawing means, and

vi. a discharge outlet at the bottom of said column.

2 An apparatus as set forth in claim l wherei n said packing beds include a ceramic packing material sup- "tamed by a permeable plate.

3. An apparatus for the continuous separation of meta and para cresols comprising:

A. a means for sulfonating mand p-cresols; and B. a desulfonation column including i. an inlet connected to said sulfonating means for introduction of a stream of sulfonated cresols into the top of said column,

ii. means for directing a diluent into said stream in the top of said column,

iii. a plurality of vertically spaced apart packing beds including ceramic packing material, adjacent beds defining open chambers there between,

iv. means for introducing steam into alternate chambers between said beds,

v. means for withdrawing volatized fractions connected to said other chambers and including first and second condensing means associated with the upper and bottom spaces to which said withdrawal means are associated, respectively, and

vi. a discharge outlet at the bottom of said column.

4. An apparatus set forth in claim 3 wherein a means for concentrating sulfuric acid formed in said column 1 is connected to said discharge outlet.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,785,776 Dated January 15, 1974 1nv'entofls) Barrymore T. Larkin Itis certified thaterror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

column-5; line 39, the word "spaces" should be deleted;

Column"6, line 41, the word "as" should be inserted after "apparatus".

Signed andds'ealed this'-11-th*day "of June 1971;.

(SEAL) Attest: I

EDWARD ummknmmm. CIMARSHALL mm: Attesting Officer Gonmiuioner of Patents FORM. (10-59) V I USCOMM-DC 60376-P69 v a U5. GOVERNMENT PRINTING QFI'ICF 1 I519 O-SGF'JSQ, 

2. An apparatus as set forth in claim 1 wherein said packing beds include a ceramic packing material supported by a permeable plate.
 3. An apparatus for the continuous separation of meta and para cresols comprising: A. a means for sulfonating m- and p-cresols; and B. a desulfonation column including i. an inlet connected to said sulfonating means for introduction of a stream of sulfonated cresols into the top of said column, ii. means for directing a diluent into said stream in the top of said column, iii. a plurality of vertically spaced apart packing beds including ceramic packing material, adjacent beds defining open chambers there between, iv. means for introducing steam into alternate chambers between said beds, v. means for withdrawing volatized fractions connected to said other chambers and including first and second condensing means associated with the upper and bottom spaces to which said withdrawal means are associated, respectively, and vi. a discharge outlet at the bottom of said column.
 4. An apparatus set forth in claim 3 wherein a means for concentrating sulfuric acid formed in said column is connected to said discharge outlet. 